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A new approach to measure functional stability of the knee based on changes in knee axis orientation
Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.ORCID iD: 0000-0002-0366-4609
2013 (English)In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 46, no 5, 855-862 p.Article in journal (Refereed) Published
Abstract [en]

There is a lack of measures that quantify functional knee stability, which is of particular relevance in knee rehabilitation. Therefore, the aim of this study was to investigate the usefulness of knee finite helical axis (FHA) variables in 33 healthy subjects during two different functional tasks; One leg side hop (SH) and Two Leg Squat (TLS), and to investigate correlations of these variables with laxity. Laxity was assessed with a KT-1000 arthrometer and the Beighton Hypermobility Score. Movements were registered with an optical motion capture system. Knee rotation and translation were defined by a six degree of freedom segment model. FHA was calculated for finite steps of 20 degrees knee flexion, based on error simulations. We computed the FHA inclination, the translation along FHA and an FHA Direction Index quantifying directional changes. All variables were repeatable (average ICCs similar to 0.97 during TLS and similar to 0.83 during SH). The lower functional knee stability in SH was reflected by a significantly higher FHA Direction Index and a larger medio-lateral FHA inclination compared to those in TLS. The superior-inferior inclination was smaller during Landing in SH compared to Take-Off and TLS. Translation along FHA was generally small as expected in healthy subjects. Beighton Hypermobility Score and KT-1000 values had weak but significant correlations with FHA Direction Index and FHA translation, which show that laxity influences the functional knee stability. We conclude that FHA measures were sensitive enough to discriminate between SH and TLS. The next step is to investigate the usability of these measures in subjects with knee injury.

Place, publisher, year, edition, pages
Oxford: Elsevier, 2013. Vol. 46, no 5, 855-862 p.
Keyword [en]
Knee joint, Kinematics, Helical axis, Side hop, Knee flexion
National Category
URN: urn:nbn:se:umu:diva-70150DOI: 10.1016/j.jbiomech.2012.12.015ISI: 000316829700002OAI: diva2:620556
Available from: 2013-05-08 Created: 2013-05-06 Last updated: 2015-01-21Bibliographically approved

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Grip, HelenaHäger, Charlotte
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PhysiotherapyDepartment of Community Medicine and Rehabilitation
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